"Another broken promise is bad news for a mobile operating system that is practically dead, and once again Microsoft has angered its small but loyal base of Windows Phone users".

"Consistent with our approach to the Windows 10 PC upgrade, we are focused on delivering a high quality experience for our customers", said Michael Fortin (Corporate VP, Core Quality, Windows and Devices Group). And now it is officially revealed that the some Lumia series devices will not get Windows 10 update, which was promised earlier. The list includes the entire Lumia range ranging from the Lumia 1520, Lumia 640, Lumia 640 XL, Lumia 930, Lumia 730 and Lumia 735 to Lumia 532, Lumia 830, Lumia 535, Lumia 635, Lumia 540, Lumia 636, Lumia 638, Lumia 430, and Lumia 435. This is true that Microsoft still needs to work a lot on its mobile update if it really wants to sell Lumia phones or upcoming, rumored Surface phones. So, the Lumia series devices like Lumia 920 and Lumia 1020 will die with Windows 8.1 OS. With Microsoft moving towards making universal apps available, mobile users can use the same app on their Windows 10 desktop or tablet for easier integration.

For the moment, some issues continue to remain unresolved, but given the fact that Windows 10 Mobile has only recently been released for Windows Phone devices, it could take a while until Microsoft manages to patch all bugs that users find on all supported handsets.

"As Windows 10 delivers significant new innovations, many older devices are not able to successfully upgrade without an impact on the customer experience", Fortin explained.

Windows 10 Mobile is set to bring new features to the mobile device, such as a better notification menu, an audio recording app, a new alarm app, new context menus, sticky keyboards, among other things.